Electrophysiological Evaluation of Synaptic Plasticity in Injured CNS - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 123

5. To obtain a baseline recording, pulses of a stimulus intensity
(40-100 s) that give 40% of the maximum amplitude

are delivered once every 20 s (0.05 Hz) for 15-30 min.
6. Induction of LTP by theta-burst stimulation (TBS): In this
technique, LTP is elicited by delivering ten bursts at 5 Hz,
with each burst containing four pulses at 100 Hz, at pulse
intensity same as what is used in baseline recording. Five TBSs
are applied with a 20-s interval between each train. This proto-
col can induce reliable NMDA-dependent LTP in CA3-CA1
synapses.
7. Induction of LTP by high-frequency stimulation: The high-
frequency stimulation consists of four trains of 100 Hz for 1 s
with an interval of 15 s. This protocol produces strong LTP in
mossy fi ber synapses, which is known to be NMDA receptor
independent.
8. Induction of LTD by low-frequency stimulation: The stimula-
tion protocol consists of 1-Hz stimulation at the test pulse
intensity for 10 min that is repeated after a 10-min interval.
This protocol can induce input-specifi c NMDA receptor-
dependent LTD in CA3-CA1 synapses in adult rodents.

μ A, 100 μ

Whole-cell patch clamp recordings are made from visually identifi ed
neurons in neocortical or hippocampal slices under current- or voltage-
clamp mode. The same stimulating protocols as in FPR can be
applied to evaluate short-term and long-term synaptic plasticity.

3.4. Whole-Cell Patch
Clamp Recording for
Evaluation of Synaptic
Plasticity

1. In each trace of evoked fi eld potential response, a single current
pulse delivered to afferent fi bers (e.g., white matter) to the
cortex causes a rapid and big stimulus artifact, which is typically
followed by two short latency negative potentials. The fi rst one
corresponds to compound action potentials (APs) originated
from antidromic stimulation of axons of cortical neurons close
to the recording pipette. The second is the postsynaptic poten-
tial evoked by activating of the afferent fi bers, and is termed
fEPSP (Fig. 4c ).
2. Typically, the initial slope of the fEPSP (mV/ms) during the
near-linear rising phase (e.g., ~600

3.5. Data Analysis

s) or fEPSP peak ampli-
tude is used for measuring synaptic strength in experiments on
synaptic plasticity.
3. Paired pulse ratio is calculated by dividing the amplitude of the
second fEPSP by the amplitude of fi rst fEPSP.
4. Data obtained from LTP and LTD experiments are usually
expressed as mean percentage of baseline fEPSP ± SEM.

μ